Field of the Invention
The present invention relates to a holding apparatus, an imprint apparatus, and an article manufacturing method using the imprint apparatus.
Description of the Related Art
As the demand for microfabrication of semiconductor devices increases, not only a conventional photolithography technology but also a microfabrication technology in which an uncured resin on a substrate is molded using a mold to thereby form a resin pattern on the substrate have been receiving attention. This technology is also referred to as an “imprint technology”, by which a fine structure with dimensions of a few nanometers can be formed on a substrate. One example of imprint technologies includes a photo-curing method. An imprint apparatus employing the photo-curing method first applies an ultraviolet curable resin (imprint resin, photocurable resin) to a shot area (imprint area) on a substrate (wafer). Next, the resin (uncured resin) is molded by a mold. After the ultraviolet curable resin is irradiated with ultraviolet light for curing, the cured resin is released from the mold, whereby a resin pattern is formed on the substrate.
In general, a holding apparatus that holds a mold, which is provided in the imprint apparatus, includes a magnification correction mechanism that corrects pattern magnification error generated during semiconductor processing. The magnification correction mechanism is constituted by a drive unit, a sensor for controlling the drive amount of the drive unit, and the like, and is provided at a plurality of locations so as to enclose the outer peripheral portion of a mold. In this case, the drive unit imparts an external force to a mold, and deforms the mold itself to thereby correct the pattern shape formed in the mold. In such cases, since the pattern shape may affect the overlay accuracy of patterns, correction with high accuracy of a few nanometers or less is required for dealing with microfabrication of pattern imprinting. Japanese Patent Laid-Open No. 2008-504141 discloses a correction device that performs magnification correction by applying a compressive force to the lateral surfaces of a mold.
Here, in the imprint apparatus, a mold is typically held via a mold chuck (mold attraction mechanism) that allows direct attraction (e.g., vacuum attraction) of the mold. The correction device disclosed in Japanese Patent Laid-Open No. 2008-504141 performs the magnification correction described above in a state where the mold chuck holds the mold in the mold-printing direction by attraction. Thus, a frictional force is exerted to the contact surface between the mold and the mold chuck in the direction of the compressive force to be applied by the correction device. In other words, the correction device performs magnification correction by rubbing the contact surface by applying a force greater than a frictional force to a mold. In such cases, since the contact areas for both of the mold and the mold chuck are relatively moved to each other, the contact state of both the mold and the mold chuck changes during driving of the correction device, and thus, a frictional force at the contact surface also varies. Hence, the ununiformed distortion occurs at the pattern portion formed in the mold, and thus, a desired pattern shape may not be obtained. Also, when rubbing occurs at the contact surface between the mold and the mold chuck, particles (dust) occur. Since such particles adhere to the surface of the mold or are entrapped between the mold and the substrate, the formation of a desired resin pattern may be inhibited.